In order to change the cipherkey go to the Location: \apache-tomcat-7\webapps\hi\WEB-INF\classes
In customAuthetication.properties change the value of cipherKey as shown in the following screenshot.
After making the changes save the file.
Note: The length of cipher key should be 16 and the cipher key used in the properties files should be similar to that of the key used while encrypting the token.